Thursday, April 30, 2009

More than a million asteroids have been discovered and named in our Solar System. Many more are discovered each year.

If an asteroid with a diameter of more than 1 km struck the earth, it would result in permanent climate change and the likely eradication of human life. For this reason, scientists have attempted to map as many of them as possible. It's still not a perfect system, however. Last month the previously undiscovered asteroid 2009 DD45 whizzed past our planet, visible with the naked eye from the southern hemisphere, at 20 km per second only 66,000 km above the surface.

Asteroids get closer than this all the time, so scientists say there's nothing to fear from 2009 DD45.

The vast majority of asteroids are located in the belt between Mars and Jupiter. Their combined mass is less than that of the Earth's moon. There are 26 known asteroids larger than 200 km in diameter. We probably know more than 99% of the large asteroids, more than 100 km in diameter, but very few of the smaller ones. There are probably more than a million with diameters of 1 km or more. Most are in relatively circular orbits, but some are much more eccentric, which can sometimes bring their flight paths uncomfortably close to Earth.

The first asteroid was discovered on January 1, 1801, by GiuseppiPiazzi. He believed he had discovered a small planet, and named it Ceres, after the Roman goddess of grain. Within the next few years, asteroids Pallas, Vesta, and Juno were discovered. By the end of the 19th century, scientists had discovered thousands of asteroids.

Ceres is the largest known asteroid, with a diameter of 590 miles. This is large enough so that gravity has given it a roughly spherical shape. For this reason, astronomers have re-classified Ceres as a dwarf planet, like Pluto.

The photo to the right was taken by the Hubble telescope, and is the clearest image of Ceres to date, but the dwarf planet is scheduled to be explored by unmanned NASA probes within the next five years.

In 1991 the Galileo spacecraft gave us our first up close images of asteroids, photographing Ida and Gaspra on its way to Jupiter.

Ida is especially interesting because it has its own tiny satellite, the asteroid Dactyl (with a diameter of about 1.5 km, you can see it as a tiny dot on the right side of the photo). It is believed that several asteroids in the region were originally one big piece, which broke apart after a collision with another object. In fact, many asteroids may be part of binary systems or even small groups of satellites revolving around larger neighbors.

Perhaps the most notable asteroid of all is Apophis, whose orbit brings it very close to Earth once every few years. It is "only" 350 meters across, but will be in our vicinity in 2029. Scientists estimate a 1 in 45,000 chance that Apophis will collide with Earth in 2029. If this were to happen, the impact would release 880 megatons of energy. When Meteor Crater, Arizona was formed (pictured at the top of this post), only 3 - 10 megatons were released. If Apophis hit Earth on the land, the impact would kill millions. If it struck the water, it would create devastating tsunamis in all directions.

There's no need to panic. Space is filled with asteroids, comets, and other space debris that could impact the Earth at any time. NASA and ESA are developing plans to visit and possibly deflect such objects if they get too close to our planet, in addition to mapping as many objects as possible so that we can predict an impact with enough time to react. Learning about our rogue neighbors, the asteroids, is a critical step towards preventing future catastrophes.

Wednesday, April 29, 2009

The most important plant-eaters at the end of the age of dinosaurs were the hadrosaurids, or duck-billed dinosaurs.

Hadrosaurus was one of the first dinosaurs discovered in North America, and one of the first nearly complete skeletons ever found. First noticed in a marl pit in 1838 near Haddonfield, New Jersey, it was nearly twenty years before the fossilized remains were recognized, named, and excavated.

Few remains of hadrosaurus have been found since this original specimen (now on display at the Philadelphia Academy of Science), but a host of similar dinosaurs with duck-bill shaped skulls are now categorized as hadrosaurids. Several distinct features set hadrosaurs apart from other plant-eaters of the time, especially their beaks and unusual head crests.

Hadrosaurs evolved along with the development of flowering plants, from 100 to 65 million years ago, and may have risen to prominence because they were able to eat this new food source.

It was originally believed that the duckbill shaped beak suggested that hadrosaurs lived in water. The tail, which has a finned shape like a crocodile's, would seem to support this idea. But with few other body parts appearing to be adapted to an aquatic existence, this theory has now been widely discredited. Still, hadrosaurs would have had no problem crossing a river or wading through a swamp. Their limbs allowed them to walk on all fours or on just the two rear legs.

The hadrosaur neck is S-shaped, consistent with a low feeder, like a modern horse or buffalo. Different animals have different shaped beaks, however: narrow-beaked dinosaurs would have been selective eaters, while broad-mouthed dinosaurs would have eaten great mouthfuls of plants indiscriminately.

Hadrosaurs had teeth only in the cheek region, near the back of the jaw. They were closely packed into sections of fifty teeth or more, with columns of "back ups" as teeth became broken by cutting through rough plant material. Some hadrosaurs had more than a thousand teeth at a time, which were regularly replaced, like all dinosaur teeth, or like modern crocodiles and sharks.

The hadrosaur group evolved rapidly, and into many varied forms. They have been found in every continent, except for Australia and Africa. Some were more than 12 meters long, and weighed up to 5 tons. Animals this large had to be fast and agile enough to avoid predators, which required massive amounts of energy from food. Evidence suggests that hadrosaurs lived in groups, and when they ate, hadrosaur groups must have denuded entire forests to satisfy their need for food.

Many hadrosaurs had impressive crests, which consisted of hollow tubes connected to the nasal passages. There are many theories about how these crests developed.

One idea is that the hadrosaurs may have relied heavily on their sense of smell, and that these tubes amplified this sense, helping the animal to detect slight variations in the scents in the air. Another possibility is that the crest was a sort of communication device. Air snorted through the tube would have made a loud honking sound, audible for miles. This may have been used for long distance communication, to warn others of the species when a predator was approaching. There is no reason why these theories could not both be true.

The discovery of hadrosaurs, around the time of the US Civil War, helped establish dinosaurs as a distinctive group of animals. It also reinforced the idea that some animals had lived on earth and become extinct before the first humans. After all, there are thousands of hadrosaur remains that have been found all over the world, yet no one ever mentions seeing a living one. It was around this time that Charles Darwin published his theory of natural selection, explaining that life on earth might be much older than anyone had previously suspected.

The river begins high in the Andes Mountains, and holds more water than all of the rivers in China combined. In some places it is almost 300 feet deep.As for the jungle itself, visitors must deal with pirhanas, vampire bats, electric eels, jaguars, anacondas, and abhorrent parasites that swim up one's penis or vagina to burrow into the host's spine. The humidity breeds huge clouds of gnats and mosquitoes, which are miserable to deal with in addition to causing malaria and yellow fever. Mold grows instantaneously, ruining equipment and making food inedible.

For all these reasons and more, the region was one of the last places on earth to be explored and mapped. Rumors persisted of a legendary city deep in the rain forest, built by a sophisticated civilization with monumental architecture.

"Colonel" Percy Harrison Fawcett, our story's hero, had already mapped much of Brazil and Peru when he set out to find what he called the lost city of Z in 1925. What a bizarre character! Fawcett is a world famous explorer and military hero, with bombastic ambition and a peculiar obsession with the occult. He brings a small group, including his debonair eighteen year-old son Jack, determined to map the Brazilian rain forest and either prove or debunk the Z legend once and for all.The entire group mysteriously disappears and is never heard from again. Most assume they were victims of the hostile conditions, while some believe they found the city of Z and loved it too much to leave. In subsequent decades, dozens of parties tried to retrace Fawcett's steps, only to be killed or retreat in despair.The author includes tales of adventure from his own expeditions to the rain forest in modern times. David Grann became interested in the Fawcett story, and has since tried to solve the eighty year-old mystery of what happened to the world's greatest explorer.

The Lost City of Z is history and travel writing at its best, filled with fascinating stories about cannibals and shrunken heads.

Although it was only published two months ago, Z has already been optioned for a film by Paramount. You heard it here first.

Gay romance novels are usually not at the top of the literary food chain, which is why I was somewhat surprised by how good this book was. It's beautifully constructed: rich with longing and unrequited love, just like any "traditional" romance novel, but with more action and sexuality to keep an audience of gay men interested.

It takes place in England during the first years of the British Civil War, beginning in 1642. David Caverly is a teenage boy who lives on his pious, hardworking father's farm. Life is serious, with little time for anything besides toil and prayer.One day, however, David's father brings home an apprentice named Jonathan to work in his blacksmith shop. Jonathan is a hunky Puritan boy who will be working on the family farm and sleeping in David's room. Like brothers. Delicious.

Soon the two young men start fooling around, and even fall in love. In 1642 , so naturally homosexuality is considered a sin and capital crime, as is unfortunately still the case today in many places. The two lovers have to keep their relationship very discreet, or face terrible consequences.

Transgressions doesn't fixate on the injustices of homophobia, however. It's a romance novel.

A local young woman feels jealous because David isn't attracted to her, and publicly accuses him of getting her pregnant. The lie is widely believed, and David is forced to leave town in disgrace. He becomes a soldier in the Royal Army, defending King Charles. Jonathan misses his departed boyfriend, and leaves his indenture at the blacksmith shop to try to find him, leading him on adventures of his own.I enjoyed the story well enough, and the development of David and Jonathan's characters was outstanding. Their names honor two biblical characters, which creates a delightful subtext throughout the book. It is this attention to elegance and detail that makes the book romantic and not merely sexual.

Although there is a considerable amount of sex. Erastes has won awards for her erotic writing, and I can understand why. This book masters the art of long, slow build up. When the young men spend their first night as bunk mates, they're very embarassed but curious about one another's bodies. Jonathan, the Puritan, actually stands facing the corner while David gets undressed, too prudish to even look at another man's naked body. This doesn't last long: they start by innocently wrestling and skinny dipping, and their relationship develops for several chapters before they have real sex. It's a terrific build up, and I don't mind telling you I had a hard on the entire time.Of course, Transgressions is not for everyone. Straight guys would find it of absolutely no interest, in spite of the good war scenes. It's obviously intended for gay men, but the author is a woman and other women might enjoy it. Readers of typical, heterosexual romance novels could find it a giddy thrill. Gay fiction, especially gay erotica, is usually pretty terrible. I'm pleased to say this book was a most lovely exception.

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Hansisgreat is your #1 source for leisure reading, light cultural interest stories, and shirtless male models. Checking out guys on the internet is good... but there's also more to life. I'm going for the feel of Men's Health or Cosmopolitan magazine, only with slightly brainier articles.

All the books I review are available in the Hansisgreat Store, so that you can buy them if you wish.Hans (who's great, by the way) is in his early 30s, studiously handsome, a Taurus, and lives in New Jersey, USA. His interests include playing sports, dinosaurs, outer space, history, and reading. He can solve Rubik's Cube, and knows how to make origami animals. His favorite flower is morning glory, and his favorite pasta is bowties.

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